A common injury, especially among athletes and people of advancing age, is the complete or partial detachment of tendons, ligaments, or other soft tissues from bone. Tissue detachment may occur during a fall, by overexertion, or for a variety of other reasons. Surgical intervention is often needed, particularly when tissue is completely detached from its associated bone. Currently available devices for tissue attachment include screws, staples, suture anchors, and tacks. Currently available devices for patients of advancing age can be particularly insufficient due to soft and weak bones leading to inadequate suture-to-anchor fixation.
Arthroscopic knot tying is commonly practiced in shoulder rotator cuff and instability procedures. Typically, an anchor loaded with suture is first attached to bone. The suture is normally slidably attached to the anchor through an eyelet or around a post, such that a single length of suture has two free limbs. One limb of the suture is passed through soft tissue to be repaired such as a tendon or labrum. The two ends of the suture are then tied to each other, thereby capturing the soft tissue in a loop with the anchor. Upon tightening the loop, the soft tissue is approximated to the bone via the anchor.
Surgeons typically tie the suture ends using a surgical sliding knot such as the Tennessee Slider or Duncan Loop. After advancing the knot distally to tighten the loop, a number of additional half hitches or other knots are tied in an effort to secure the new location of the sliding knot. The additional knots are needed because a conventional sliding knot used in current repair constructs does not provide the necessary protection against loosening or slippage, especially when tension is placed primarily on the limbs of the loop. The generally accepted practice is to follow the sliding knot with at least three reversed half hitches on alternating posts of the suture.
Before one or more half hitches or other knots can be added to the sliding knot, however, there exists a potential for the sliding knot to slip, that is, for the loop to enlarge as the tissue places tension on the loop. This has been referred to as “loop security” and can reportedly occur even in the hands of very experienced surgeons. Sometimes, even fully-tied knots may slip. In addition to this “loop security” problem, conventional knots typically have an overall size that can be obstructive or intrusive, especially in tight joints, which may damage cartilage or other tissue by abrasion with the knot.
Suture anchor systems with sliding and locking knots for repairing torn or damaged tissue include U.S. Pat. No. 6,767,037 by Wenstrom, Jr. Other suture anchor systems suited especially for meniscal repair are disclosed in U.S. Pat. No. 7,390,332 by Selvitelli et al. and are utilized in the OmniSpan™ meniscal repair system commercially available from DePuy Mitek Inc., 325 Paramount Drive, Raynham, Mass. 02767. Screw-type anchors normally require anchor attachment before operating sutures, which can lead to challenges related to the connection between the suture and the tissue.
There are a number of suture implant systems which proclaim to be “knotless,” that is, to not require a surgeon to tie a knot during surgery. Many such systems control tension on tissue by the depth to which an anchor is driven into bone. U.S. Pat. Nos. 5,782,864 and 7,381,213 by Lizardi disclose certain types of suture anchors that capture a fixed-length loop of suture. Adjustable loop knotless anchor assemblies utilizing an anchor element inserted into a sleeve are described by Thal in U.S. Pat. Nos. 5,569,306 and 6,045,574 and in U.S. Patent Application Publication No. 2009/0138042. Other systems having clamps or other locking mechanisms include U.S. Pat. No. 5,702,397 by Goble et al. and U.S. Patent Application Publication No. 2008/0091237 by Schwartz et al. Present, so-called “knotless” designs, however, generally suffer from inadequate suture-to-anchor fixation and/or inadequate anchor-to-bone fixation, among other deficiencies.
It is therefore desirable to provide systems, devices, and methods for use in soft tissue repair that are robust and strong, yet minimize or eliminate the number and size of knots to be tied by a surgeon, particularly during arthroscopic repair procedures.